I. Field of the Invention
This invention relates to electronic scan antennas operating in the millimeter and microwave regions of the frequency spectrum and, more particularly, to a microstrip electronic scan antenna array which is capable of producing 360 degree scanning in radar systems and the like.
II. Description of the Prior Art
Electronic scan antennas for radar systems and the like are often used in applications where the requirements of size, weight and operating reliability rule out the use of older mechanical scanning systems. Examples of such applications are military and commercial aircraft, terminal homing weapons and remotely piloted vehicles. Although electronic scanning has been provided by utilizing phase shifting techniques, systems using these techniques are usually complex in construction and costly to fabricate. The problems are exacerbated when a 360 degree scan is needed for applications, such as tank, terminal homing weapon and remotely piloted vehicle radar systems, for example, because the size, weight and cost of the resulting scanning systems needed for these applications exceed the size, weight and cost limitations imposed by the application. Furthermore, since much of the work in this area today is being carried out utilizing the microstrip transmission line medium of propagation, it is desirable to efficiently accomplish electronic scanning at millimeter wave frequencies utilizing scanning equipment and techniques suitable for use with the microstrip transmission line propagation medium.